Alloy steel



' tion,-as the process of oxidizing the carbon v "alloying metal,results in a substantlally 49 sequent waste, of the valuable alloyingeleofjthe charge. The freshly reduced alloyingmetal is in direct contactwith the melting steel,. and therefore. the best conditions hatented'Aijug unorsrnnn w ing elements, in the already reduced metallic state,mostly in the form of a ferro-aL.

' loy, are added to a molten bath of steel. For example, to obtain therespective steels thereof, term-manganese, ferro-chromium,ferro-titanium, form-tungsten, .ferro-vanadium, term-uranium, ferrc-molybdenum,

. term-nickel or metallic nickel and ferro-cobalt or cobalt metal, areadded't'o'the steel, in the molten state in the furnace, or after it istapped in. the ladle. -'As--the regular commercial grades of suchferro-alloys conv tain an appreciable amount of carbon, this practiceintroduces an undue amount of carbon in the steel. If special grades oflowcarbon-lerro-alloys arn used, the cost of such alloysis comparativelyso high as to prohib-' itively' increase the cost of steel produced,These defects are especially apparent in the case'of steels where thecontent of the alloy- 39 ing element'has to be high and the carboncontent low, as in the case of the so-called stainless steels or irons,which have a; '"'chromium content'o f between 9 and 15% v and a lowcarbon contonh It is not commercially practicable to usethe regular highcarbon ferro-alloys, and:

then decarbonize the steel after their addiis accompanied byan'oxidation, and con- .ments. w Jul: 5. V ,Another deficiency of theexisting" methods 'ofmanufacturmg alloy steels, by the addition ofmetallic 'ferro-alloys to -molten steel, is the henomenon ofsegregation. The alloy being added in the solid state in the form oflumps scattered .oyer the surface of the molten steel, causes points: ofconcentration of the alloying element at the 1 location of each ofthe'lumpsi 'As the'steelis' tapped immediately after melting of-the lums in order to avoid an undue oxidation 1 of t e alloying element,"the'sepoints of higher concentration have no. opportunity V to equalizethemselves over the. ent1r'e mass of metal by difiusion. Moreover, theferro --ment content will persist in I the stee on mixed together, andthen melted. On the 1923, Serial m5. 650,157.

alloys have various constituents of different meltingpoints and de eesof, solubility, as p for example the carbides in the ordinary grades ofalloy. Such carbides have a higher melting 'point than the remainder ofthe alloy. Such a carbide-containi ferro alloy, when added to moltensteel, Will have. the result that when the rest of the alloy will becompletel assimilated, the carbide content will still e in the solidstate, floatg in the molten steel, without giving up its alloyingelement content to the bath. Such solid particles with a high alloy' 1ele- 7 0 solidification and present, segregation...

I overcome the above mentioned difiicul ties by introducing the alloyingmetal in unreduced form, such as an oxide or an-ore, and reducing itsimultaneously with the melting of the cold metal, such as the steelscrap to be melted. The alloying metal 0rd or the scrap and the reducingagent may all be charged cold into the furnace, preferably other hand, amolten bath containing a part of the iron and steel, together with thereducing agent if desired, may be formed, and then the cold scrap andalloying ore, with or withouta reducing agent, may

or steel. In each case thejuninelted metal,

' such as steel scrap, is a'substantial qua tit go;

of proportion ofthe' whole charge-niche so that the dissemination ofthe. alloyin metal into the steel which is being melted simultaneouslywith the reduction of the thorough dissemination throughout the body areobtained for the alloying'and uniform out-the. molten steel,

tion*-of -added fluxing material, generally.

lime, absorbing and neutraliai" the I oxidized r'educf agent togetherwith undesirable 'metalloi ,such. as phosphorus and sulphur, .cause-.;a"refining ofthe steel to take it be as w 7 charged into the furnace. Ineither case, I the alloying ore is reduced simultaneously a with themelting "of some or all of thev iron 10o;- disseminating-of the all gymgmetal throughe alloying element f isobtained from acheap source Thein itplace simultaneous] with p the .production of the alloy and me ting ofthe scrap.

T e process may be carried out inthefol-- lowing manner: I? g 1 e steelor ironscrap desired to be melted to the alloy steel paratively smallsizes, such as borings, turnetc, is mixed with a reducing agent, w ichmay be a metallic reducing agent such as silicon, manganese, calciummagnesium or I the like, either alone or in combination with acarbonaceous reducing material, for mpreferably in the ofreducin arefigure centage of. alloying weight of finished steel.

asto eflectiyely'remove by chemical-combination the roduct formed byoxidation of a metallic re ucing agent, such as silicon. In

the case of silicon,

the silica produced by its oxidation goes into chemical combination withthe slag, principallyin theform of calcium silicate,.and is therebyremoved from the metal. The

' the flux, therefore,'is" the prevention of "the presence of thereducing agent in the 'finished steel. The

' ders the oxide more amenabletoreduction mixture "of raw materials ischarged into any well ten, it is advantageous temperature in' order 8traces of'the reducingscrap or pig, the a-llOyingpre, I agent .and theslag-forming or at short intervals to hy-"the reducing agent;

' 'tion then ismelted-and the reduced alloying or electric furnace at afor the reaction. After electricfurnace, Th

proceeds at the same time the scrap element is directly in contact withthe melt ng scrap and is readily absorbed in the liquid steel;

As-this operation takes lace in the presence uxing materia s, moltenscrap proceeds simultaneously. The

furnace such as an open-hearth, or crucible, temperature suitable "thereaction is 'complete and the entire charge thorougl-ilymoltoraisethe'furnace to eliminate .;the-: last ageht in the finished steel,acceleratin ,theefiect produced; by fluxing agents-ad ed for this heprocess i's-particularly applicable to the manufacture ofalloy'steel ,oriron in an e, furnace may be operated continuously, 3 the steel Lor ironb'ei tapped out as collected, and the unmelt d the reducing chargedcontinuously the bath, which is continuously .-mainta ined preferablyselected in comagent andalloying raw material give the requisiteperpractical result achieved by flux also combines with the "refractorygangue elements of ore and rena The reducing reac- .a-refining of the asabove describedknown steel makingam the hearth. This allows an electricfurnace to be operated continuously at sub- ...stantially constant load,thus obviating the. ,power fluctuations incident toipleriodicoper"'a'tion of 'a'n"electric sufelt' rna'ce.

The most generally .ducing a con meta or I silicon alloy containing oneof the alloyin metals may also be 'advantageously'use I For instance, inthe case of the manufacture =,of-so-called stainless steel 21'silico-ch'ro-' mium alloy may be added to the rawfcold charge and itssilicon content utilized-tore duce a further quantity of chromium fromchrome orepresent in the charge. This procedure'is especiallyadvantageous in the case of a steel containing a alloying element.

T-tended as a'term of'gen'eral description and 7 not of limitation, andis intended to include .not only substantially pure silicon, but alsosilicon alloyed w'thother metals or metalloids.

In the case-of alloy steels jcont-aini-ng' a plurality .ofalloyingelements,

*the raw materials in the right containingthe plural elements, beingcharged together with the scrap and reducing agent. The flux maybe addedsepa- -rately or' the raw alloying materials may be selected of'such acomposition as to have in their gangue the 'nents,

together and the adapted metallic. re- 7 nt is ferro-siliconlHowever,-s1liany other silicon alloysuchzas a The term silicon reducingagent is innecessary fluxing compohigh percentage of the this; procedure may be carried out in the same-manner,

proportions Thesteel scrap and the ore-may be mixed mixture charged.into the rnace 'or' the steel scrap and the ore may be introduced inseparate batches-"or charges, "so long as they simultaneously or. withinthat the melting down of the scrap will proreduction ofthe' ore.

used, such as a mixtureof carbonaceous and metallic reducing agentsi'orseveral different jmetallic reducing stance, a ferro-silicon alloycontaining car bon'may he'nse'd, both its a bntents being utilized -for,=th'e reduction *YJPIH'POSBQQAISO any reducing agents" origin lliypresentinjthe' sc'ra I I use thus eli-minating their presence-dram arechargedsubstantially such time interval ceed substantiallysimultaneously wants I .Also a plurality 'ofreducing' agent fma 1agents. "For in- .325 silicon and carbon may be effectively the chargewill have the effect "of refining.

the molten sc'rap busly with the-. melting 'o calloymg "withther-alloying'elemena ii deoxidizing If desired, after the'ineltin'gofthe chase.

is ended,.a "small,.

Silicon or erro i'ofdts metalloidleontents, -such as sulphurandphesihorus, simultanev thestgrapf'and its cleanser, before'tappin thesteel, as is the common ractice in ma ingalloy steels."

, The a vantages of this process of simultaneous melting, refining andalloying are steels or iron with a high alloy content an very low carboncontent. As such an instance may be cited the manufacture of'so calledstainless iron containing 9 to 15% chromium and less than 0.1% carbon.Also the advantages of this process are apparent in the case of alloyinga highly oxidizable and difiicultly soluble element as uranium in steel.The alloying element being produced in the nascent'state and directly incontact with the melting steel, the chances of its oxidizing or notdissolving are reduced to a minimum.' Also, as the carbon content of thefinished steel can be eliminated to any desired extent, simultaneouslyduring the process of reducing and alloying, the exact percentageofcarbon in the finished alloy steel can be arrived at more accurately byrecarburizing before tapping. In the case of metallic reducing agentsbeing used, their presence in the finlshed steel is practicallyeliminated by the action of fluxes. Thus by the process of thisinvention a steel of predetermined given composition can be moreaccurately produced. than by the use of ferro-alloys. Also by thisprocess, as the valuable alloying elements do not exist at 7 any time inthe metallic state, unless disas in the older processes, there is noloss sufiered through oxidation, rendering th s1l1con re ucing agent andsteelscrap and "an nnreduced chronium ,cOmpound solved and alloyed inthe steelitself, and as after their solution in the steel there is nooccasion to subject such steel to an oxidizing process forremoval ofcarbon, for instance,

process extremely ec0nomical.- The charge put into the furnace containsa suflicient proportion of steel scrap so that themetal as tappedfromthe furnace is a finished steel, as contrasted with a cast iron" ora ferro-alloy. The term steel, however, as herein employed, is intendedas a term of general definition and not of limitation, and

is intended to include steels having very low carbon and metalloidcontents and which are sometimes called irons, as for example, the

- sorbmg lime containln flux material and so-called stainless irons.

The process also assures a thorough and uniform dissemination of thealloying metal throughout the body of the molten iron or Y steel beforetapping. j While the preferredimethod of carrying out my processhas-been specificall de. scribed, it is to be understood that t e-1nvention is not limited to all of the described details, but may beotherwise embodied in processes of making alloy steels or irons, ivithinthe scope of the following claims.

' Iclaim:

1. The process of making chrome steel 68..

chrome steel in the furnace, tapping the steel Y into the bath asrefluired a silicon reducing agent and a meta oid-absorbinglime-contaimng flux material and steel scrap and an unreduced chromiumcompound in amounts sufficient to furnish the major portion, if not all,of the iron and chromium contents of the steel and proportioned tomaintain the desired composition of the steel bath, substantially asdescribed.

2. The process of making alloy steel, comtherefrom from time to time,and charging prising maintaining a molten bath of alloy steel in afurnace, tapping the steel there-' from from time to time, and chargininto the bath as required a metallic re ucing agent and ametalloid-absorbing lime-con.- taining fiux material and steel scrap andan unreduced compound of the alloying metal .in amounts suflicient tofurnish the major portion, if'not all, of the iron aludalloyin metalcontents of the steel and p'roportione to maintain the desiredcomposition of the steel, substantially as described. 3. The process ofmaking chrome steel, comprising maintaining amolten both ofchrome steelin a furnace, and charging intothe bath as required a silicon reducingagent and steel scrap and an'unreduced. chronium compound in amountssufiicient to' furnish the major portion, if not all, of the iron andchromium contents of the steel and proportioned to maintain the desiredcomposition of the steel bath, substantially as described. 4. Theprocess of making chrome steel, comprisin forming a. charge containing ain amounts sufiicient'to furnish the major portron, if not all, of theiron and chromium contents :of the steel, and simultaneously melting'thecharge and reducing the chro- "15 steel scrap and an unre need chroniumcompound {amounts suflicient to. furnish the major portion, if not all,of the iron and...

scribed.

my hand.

BYRAMJI n. SAKLATWALLA.

'i chromiuni content-s of'the steel, and simul: vtaneously melting-thecharge, reducing the chromium- -from its unreduced compound andrefining. the steel, substantially as de- 1 I, In testimony whereof Ihave hereunto set v I Q

